Create IgnoringPatternMetacharactersUnitTest.java

BAEL-4881 Understanding the Pattern.quote method

core-java-modules/core-java-regex/src/test/java/com/baeldung/ignore/pattern/metacharacters/IgnoringPatternMetacharactersUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.ignore.pattern.metacharacters;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.junit.Test;
+
+public class IgnoringPatternMetacharactersUnitTest {
+    private static final String dollarValues = "$100.25, $100.50, $150.50, $100.50, $100.75";
+    private static final String patternStr = "$100.50";
+
+    @Test
+    public void givenPatternStringHasMetacharacters_whenPatternMatchedWithoutEscapingMetacharacters_thenNoMatchesFound() {
+        Pattern pattern = Pattern.compile(patternStr);
+        Matcher matcher = pattern.matcher(dollarValues);
+
+        int matches = 0;
+        while (matcher.find()) {
+            matches++;
+        }
+
+        assertEquals(0, matches);
+    }
+
+    @Test
+    public void givenPatternStringHasMetacharacters_whenPatternCompiledUsingManuallyMetaEscapedPattern_thenMatchingSuccessful() {
+        String metaEscapedPatternStr = "\\Q" + patternStr + "\\E";
+        Pattern pattern = Pattern.compile(metaEscapedPatternStr);
+        Matcher matcher = pattern.matcher(dollarValues);
+
+        int matches = 0;
+        while (matcher.find()) {
+            matches++;
+        }
+
+        assertEquals(2, matches);
+    }
+
+    @Test
+    public void givenPatternStringHasMetacharacters_whenPatternCompiledUsingLiteralPatternFromQuote_thenMatchingSuccessful() {
+        String literalPatternStr = Pattern.quote(patternStr);
+        Pattern pattern = Pattern.compile(literalPatternStr);
+        Matcher matcher = pattern.matcher(dollarValues);
+
+        int matches = 0;
+        while (matcher.find()) {
+            matches++;
+        }
+
+        assertEquals(2, matches);
+    }
+}